I would just ride the current stuff until the day it dies. I have a 20 year old 7speed shimano 105 group and I love it. It works perfectly and is not in the least bit touchy.
One nice upgrade that I have considered would be 7 speed brifters. That would be sweet! I don't know that modern components would yield enough of an improvement to justify the cost. Have you ridden any modern groups? Maybe you should test ride some of the modern bikes at the LBS?
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